The present invention relates to a method of deposition of an absorbing material upon a plastic/glass substrate by vacuum coating at an angle of inclination between 5xc2x0 to 30xc2x0 and using a mask on the evaporation source to produce a graded film material. More particularly, the present invention relates to a method for the preparation of graded density absorbing film useful as an antiglare optical device for protecting the eyes by reducing the glare by absorbing the light intensity falling upon it in a non-uniform fashion.
The necessity of Night driving filter was felt as in the night time It becomes very difficult to drive on the high ways due to the radiations falling on the eye of incoming vehicles on the driver""s eye. The excessive radiations falling on the eye makes the eye pupil to close resulting in the darkness of the view in front of the driver and accidents occur. Also the UV and IR content of the radiations make the eyes prone to cataract and other diseases. This made it essential to have device which removes this excessive radiations.
During night driving, the headlights of the vehicles approaching in the opposite direction emit radiations in the wavelength of 320-400 nm and 750-1400 nm. These radiations blind the driver due to which a number of accidents occur in the night. The frequent blinding glare not only makes the driving difficult, but also impairs the vision. The impairment of the vision occurs due to development of cataract in the crystalline lens by the UV radiation and also retinal deterioration caused due to the thermal effects of IR radiation in the long run.
To reduce the blinding effect produced by an approaching vehicle, many plastic goggles have been manufactured. A reference may be made to the night driving plastic goggles manufactured by M/s Proview Optical Corporation, Taiwan wherein yellow colored plastic is used whose spectral profile is shown in FIG. 1. The transmission table is given as Table 2. The drawbacks with these goggles as inferred from the spectral profile are as follows:
1. It reduces the transmission in the wavelength region 300-540 nm over the entire surface area thereby it also suppresses visualisation of the road on the left side.
2. It does not completely block the blinding glare entering the eyes fro the right had side of the windshield as it is transmitting more than 70% of the radiation in the wavelength region 550-750 nm.
3. Due to selective transmission in the visible region, i.e., having absorption in the blue region, it distorts the color of the objects which might effect the recognition of the person wearing blue color clothes.
Another reference may be made to St. Martin sunglasses manufactured and distributed by M/s Thukral Optics, New Delhi wherein spectacle glasses are claimed to be used as anti-radiation for filtering out UV and IR radiation from computer monitors and TV screen as well as for night driving to prevent blind spot. However, the literature of the product does not give any spectral curve or technical clarifications justifying the use of spectacle glasses for night driving.
The main object of the present invention is to provide a method for preparing a graded density absorbing film useful as an antiglare optical device.
Another object of the present invention is to provide a method for the deposition of absorbing film material upon plastic/glass substrate by vacuum coating on a inclined substrate with angel of inclination between 5xc2x0 to 30xc2x0 and using a mask on the evaporation source.
Still another object of the present invention is to provide a method for the preparation of an antiglare optical device for protecting the eyes of the automobile driver during night driving.
Yet another object of the present invention is to provide a method for the preparation of an antiglare device to protect the automobile drivers eye from radiation in the wavelength range 320-400 nm and 750-1400 nm.
One more object of the present invention is to prevent impairment of vision due to development of cataract in the crystalline lens by the UV radiation and also retinal deterioration caused due to the thermal effects of IR radiation in the long run.
The present invention relates to a method of deposition of an absorbing material upon a plastic/glass substrate by vacuum coating at an angle of inclination between 5xc2x0 to 30xc2x0 and using a mask on the evaporation source to produce a graded film material. More particularly, the present invention relates to a method for the preparation of graded density absorbing film useful as an antiglare optical device for protecting the eyes by reducing the glare by absorbing the light intensity falling upon it on a non-uniform fashion.
Accordingly, the present invention provides a method of manufacturing a coated substrate to be used as but not limited to automobile anti-glare filter, said method comprising providing a transparent substrate made of glass or synthetic material, coating a gradient density absorbing film on one side of the substrate kept at an inclined position with an angle of inclination varying between 5xc2x0 to 30xc2x0 with respect to a evaporation source, masking the evaporation source during the deposition of the absorbing material and coating the substrate with an Anti Reflection (AR) material on both surfaces thereby obtaining the anti glare optical device.
In an embodiment of the present invention, the thickness of the first coating is determined in terms of transmission of the gradient density absorbing film.
In another embodiment of the present invention, the deposition of the first coating is done so as to obtain the following transmission data on the substrate:
In another embodiment of the present invention, the evaporation source is a tungsten spiral filament.
In still another embodiment of the present invention, the evaporation is done in a vacuum coating plant maintained at 2xc3x9710xe2x88x925 mb to 1xc3x9710xe2x88x926 mb.
In yet another embodiment of the present invention, the absorbing material is selected from the group comprising of Inconel, Rhodium, Palladium, Nichrome, chromium and mixtures mixtures thereof.
In one more embodiment of the present invention, the AR material is selected from the group comprising of Magnesium fluoride, Silicon dioxide and mixtures thereof.
In one another embodiment of the present invention, the synthetic material is polycarbonate plastic.
In an embodiment of the present invention, after the absorbing material is coated, the chamber is brought to normal atmospheric pressure and the coated substrate is placed horizontal w.r.t. evaporating source, the chamber is evacuated to get the same vacuum and the AR material is evaporated on both sides.
The present invention further provides a method of manufacturing an improved anti glare optical device for automobiles, said method comprising: providing a transparent substrate made of glass or synthetic material, coating a gradient density absorbing film on one side of the substrate kept at an inclined position with an angle of inclination varying between 5xc2x0 to 30xc2x0 with respect to a evaporation source, masking the evaporation source during the deposition of the absorbing material and coating the substrate with Anti Reflection material on both surfaces thereby obtaining the anti glare optical device.
In an embodiment of the present invention, the thickness of the first coating is determined in terms of transmission of the gradient density absorbing film.
In another embodiment of the present invention, the deposition of the first coating is done so as to obtain the following transmission data on the substrate:
In still another embodiment of the present invention, the evaporation source is a tungsten spiral filament.
In yet another embodiment of the present invention, the evaporation is done in a vacuum coating plant maintained at 2xc3x9710xe2x88x925 mb to 1xc3x9710xe2x88x926 mb.
In one more embodiment of the present invention, the absorbing material is selected from the group comprising of Inconel, Rhodium, Palladium, Nichrome, and chromium or mixtures thereof.
In one another embodiment of the present invention, the AR material is selected from the group comprising of Magnesium fluoride and Silicon dioxide.
In an embodiment of the present invention, the synthetic material is a polycarbonate plastic.
In another embodiment of the present invention, after the absorbing material is coated, the chamber is brought to normal atmospheric pressure and the coated substrate is placed horizontal w.r.t. the evaporating source, the chamber is evacuated to get the same vacuum and the AR material is evaporated on both sides.
The present invention also provides an improved coated article to be used as but not limited to automobile anti-glare filter, said article comprising a substrate made of transparent material coated at one side with a gradient density absorbing film, said gradient density absorbing film is deposited at an angle of inclination of 5xc2x0 to 30xc2x0 w.r.t. an evaporating source, and coated on both the sides with an AR material.
In an embodiment of the present invention, the thickness of the first coating is determined in terms of transmission of the gradient density absorbing film.
In another embodiment of the present invention, the thickness of the first coating is such that it produces the following transmission data on the substrate:
In still another embodiment of the present invention, the evaporation source is a tungsten spiral filament.
In yet another embodiment of the present invention, the evaporation is done in a vacuum coating plant maintained at 2xc3x9710xe2x88x925 mb to 1xc3x9710xe2x88x926 mb.
In one more embodiment of the present invention, the absorbing material is selected from the group comprising of Inconel, Rhodium, Palladium, Nichrome, and chromium or mixtures thereof.
In one another embodiment of the present invention, the AR material is selected from the group comprising of Magnesium fluoride and Silicon dioxide.
In an embodiment of the present invention, the synthetic material is polycarbonate plastic.
In another embodiment of the present invention, the RHS of the device seen in the direction of view of the driver blocks the blinding glare coupled with attenuation in the wavelengths regions 320-400 nm in the UV and 750-1400 nm in the IR, at the same time visualisation of the road from the center as well as LHS of the filter is not reduced.
In still another embodiment of the present invention, the said article protects the driver""s eye from the radiation in the wavelength range 320-400 nm and 750-1400 nm produced by the headlights of approaching vehicles in order to prevent impairment of the vision due to development of cataract in the crystalline lens by the UV radiation and also retinal deterioration caused due to the thermal effects of IR radiation in the long run.
In yet another embodiment of the present invention the neutral transmission of the optical filter is the visible range.
In still another embodiment of the present invention, the said article does not distort the color of the object.
In yet another embodiment of the present invention, the said article is capable of being used during night driving and to be mounted in front of the driver on the automobile""s wind shield, which comprises of a gradient density absorbing film deposited upon glass/plastic substrate by vacuum coating and also Anti-Reflection (AR) coating on both surfaces of the substrate, providing adjustments on the wind shield for the compensation in the drivers eye-level and also providing means to latch on to the automobile""s ceiling when not is use, clearing the steering wheel and the driver""s head.
In one more embodiment of the present invention, the article has the following characteristics:
a) size: 300xc3x97150xc3x972-3 mm.
b) transmission at 550 nm: continuously varying along the length of the device.
c) transmission in wavelength regions:
320-400 nm: less than 10%
400-1400 nm: neutral; neutrality within xc2x110% of the value at 550 nm.
d) position of Max. and Min. transmission:
The article is mounted on the automobile""s windshield in front of the driver. The device is used by the driver during night driving to protect his/her eyes from the blinding glare (excessive visible radiation) and the radiation in the wavelength region 320-400 nm in the ultraviolet (UV) as well as in the region 750-1400 nm in the infrared (IR), produced by the headlights of the approaching vehicles in order to prevent the road accidents. The frequent blinding glare not only makes the driving difficult, but also impairs the vision. The device has the provisions to be flipped on to the windshield at the driver""s eye level during the night and to be latched on to the vehicle""s ceiling when not in use.